Printing using a sublimable coloring agent has been known and used for a number of years. This process is known as heat transfer printing and is described in U.S. Pat. No. 3,363,557 entitled "Heat Transfer of Indicia Containing Sublimable Coloring Agent", which issued on Jan. 16, 1968. The patent describes the use of sublimable dye stuffs contained in a resinous binder on a paper transfer sheet. When the sheet is pressed against a textile fabric and when sufficient heat is applied, the sublimable dye is vaporized and permeates into the textile. The technique has found its chief use in printing knitted polyester which is in part due to the stretchy nature of knitted fabrics which prevents use of conventional printing techniques. In addition, polyesters have great affinity for these type of dyes.
Other than fabric printing, no one has extended this heat transfer printing technique on a commercial basis to other decorative printing markets. A particularly interesting application would be the printing of polymeric films or polymeric coated substrates which are used, for example, in horizontal and vertical decorative surfacing. What makes the heat transferring printing technique inviting in this area is that these films and coated substrates are generally laminated under heat and pressure to a supporting substrate. Heat transfer printing could take place simultaneously with the lamination step thereby eliminating the need for a separate film printing step.
The problem encountered in bringing this to a commercial state is that the high pressure and temperature conditions of lamination cause the film or coated substrate to adhere to the heat transfer print sheet preventing the removal of the heat transfer sheet after the print has been transferred.